Digital-to-analog converters are widely used in the field of circuit electronics and are implemented with either discrete or integrated elements. Abundant literature is available on the subject.
From U.S. Pat. No. 5,376,935, which is hereby incorporated by reference, a digital-to-analog converter is known, which includes a plurality of electrically programmable floating gate transistors, each having an electrically programmable threshold voltage. Each of the transistors in the converter has its source coupled to ground, its control gate coupled to an output node, and its drain coupled to the output node via one of a plurality of switching circuits. The output node is coupled to a voltage source via a load circuit. An input circuit decodes a digital input signal to selectively generate one of a plurality of control signals at a given time in accordance with a digital input signal. Each of the control signals is for one of the switching circuits. When a transistor is coupled to the output node, the voltage level of the output node is equal to the threshold voltage of that transistor.